The U.S. Environmental Protection Agency is revising the Energy Star specification for servers to take into account significant system design changes and help buyers make effective purchasing decisions.

Over the last few years, server makers have increasingly used coprocessors to boost computing power and given memory a bigger role in processing data. While memory has gotten more power-efficient, coprocessors can suck up a lot of energy.

The upcoming, version 3.0 of the Energy Star spec for servers is aimed at helping buyers understand the power-efficiency levels of the new systems.

The Energy Star program is already used in computers, appliances, electronics and many other products. An Energy Star label is typically placed on products that meet certain power specifications.

The EPA last week sent out a letter to program participants, including server makers, to revise specifications that will "account for advances in technology and raise the bar on energy efficiency requirements for servers."

The Energy Star 2.0 certification program for servers took effect on Dec. 12, 2013. The new program will account for FPGAs (field-programmable gate arrays), which are being used in more servers. FPGAs are extremely fast at executing defined tasks but can be power hungry, which could affect the overall power efficiency rating of a server. Microsoft has built servers that rely on FPGAs to deliver more accurate Bing results, and Baidu is using FPGAs to speed up image classification and search. Intel spent $16.7 billion to buy the number-one FPGA company, Altera, and will integrate FPGAs inside its chips.

In an e-mail explaining changes to the Energy Star specification, EPA specialist Steven Hanson said, "In Version 3.0, we plan to expand our approach on auxiliary processing accelerators (APAs), which includes GPGPUs and FPGAs, as updates to the test methodology."

GPUs are being used in some of the world's fastest computers. They are also central to processing data based on machine-learning models deployed by companies like Google, Facebook and IBM.

A bigger focus will also be placed on the active state of servers, in addition to increasing the idle state power efficiency requirements. Energy Star 2.0 took active-state test benchmarks from the SERT (Server Efficiency Rating Tool) tool provided by an industry standard organization called Standard Performance Evaluation Corporation. For Energy Star 3.0, the EPA will engage other industry groups, like Green Grid, to improve on the current specification.

The new certification program will also take memory and storage into account, Hanson said.

The EPA will also work with the European Commission on Energy Star 3.0 for servers.

The Energy Star 3.0 stakeholders will collaborate on the final specification. Work on the new specification is just starting, and it could take a few years for the final version to come out.